Salams,
from the ceremony side, it is necessary to have witnesses. The way the recognition is provided is different in different societies, but since people are more likely to travel now than ever before and because for example a man may have to move temporarily for work, it becomes increasingly necessary in some societies to register the marriage.
THe Council of Imams in Canada campaign for Muslims to understand this important obligation to register the marriage. It has many reasons. One is that women are entitled to recognition and not to be hidden. This is to avoid polygamy and increase the women's rights, so she may seek help if the marriage falls apart. Different rights are given in many jurisdictions to people whether married or common law.
Yes it is important to have a Mahr for the woman. It is not symbolic. It is intended to provide women strength in the marriage. The mahr should show the man's commitment and at least some should be paid in advance and any balance should be carefully considered how it is given. THe mahr shoudl enable a woman who is in doubt of the marriage to have the financial strength to leave the matrimonial home for a while to think things through without having to initiate any proceedings for financial relief such as spousal or child support. It is separate from Spousal and child support and should be written up this way.
The principles are protection of women and we do not live in an equal society, even where the woman may earn more, she may become vulnerable from becoming pregnant or from her resources being used up if her husband does not have gainful employment. If she is a minor she needs protection from an elder, and if she has children or other dependant people she needs to consider the consequences of marriage on them, i.e. if he resources are used up for her husband rather than dependants.
IN terms of what makes a marriage in action, I think people need to love and respect the person they are with and try to learn from their differences. That is one of the most beautiful things wen people learn more because they marry someone who has different insights than they do., while having complmentary values on the major life issues. THere are so many tools out there to assist couples in building a healthy strong marriage, it really takes commitment and willingness to try technquees others have learned work well.
Marriage means putting aside alot of preconceived notions of what certain actions and words symbolize. That is a really difficutl task at times.
Salams